Energy absorption system for subterranean tool high impact loads

Abstract

A shock absorbing device for a subterranean tool features a plurality of sequentially shearing shear pins that shear after incremental relative motion of the affected components. The travel stop is located internally to a series of spaced collets supported off a ring. Impact of an impact ring segments on the travel stop segments located internally to each collet provides a shock absorbing capability as the collets are placed in tension and deflect by radial flexing in opposed directions. The relatively moving parts are rotationally locked with the last of the shear pins to shear. A backup pair of contacting shoulders are provided if the primary engaging shoulders fail to support the lower end of the tool after impact. A snap ring maintains the parts in the shifted position after impact.

We claim: 
     
       1. An impact absorbing assembly for a subterranean tool, comprising:
 a supported component comprising at least one travel stop; 
 a relatively moving component having at least one impact surface that selectively directly engages said at least one travel stop; 
 a plurality of retainers disabled by shearing at different times during movement of said relatively moving component before said at least one impact surface lands in direct contact on said at least one travel stop. 
 
     
     
       2. The assembly of  claim 1 , wherein:
 at least one of said retainers rotationally locks said components until said at least one retainer is defeated. 
 
     
     
       3. The assembly of  claim 1 , wherein:
 a first of said plurality of retainers is defeated on initial relative movement of said components. 
 
     
     
       4. The assembly of  claim 3 , wherein:
 delay in defeat of a second of said plurality of retainers is accomplished with a first axial slot on said relatively moving component having an end engaging said second of said plurality of said retainers to provide lost motion delay for defeat of said second retainer after defeat of a first of said plurality of said retainers on initial relative movement of said components. 
 
     
     
       5. The assembly of  claim 4 , wherein:
 delay in defeat of a third of said plurality of retainers is accomplished with a second axial slot on said relatively moving component having an end engaging said third of said plurality of retainers, said second axial slot end located adjacent said impact surface. 
 
     
     
       6. The assembly of  claim 5 , wherein:
 said second radial groove is spaced from a first radial groove whose end engages said second of said plurality of retainers. 
 
     
     
       7. The assembly of  claim 5 , wherein:
 said second axial slot is spaced from said first axial slot whose end engages said second of said plurality of retainers. 
 
     
     
       8. The assembly of  claim 4 , wherein:
 delay in defeat of a third of said plurality of retainers is accomplished with a second radial groove on said relatively moving component having an end engaging said third of said plurality of said retainers, said radial groove end located adjacent said impact surface. 
 
     
     
       9. The assembly of  claim 3 , wherein:
 delay in defeat of a second of said plurality of retainers is accomplished with a radial groove on said relatively moving component having an end engaging said second of said plurality of said retainers to provide lost motion delay for defeat of said second of said plurality of said retainers after defeat of a first retainer on initial relative movement of said components. 
 
     
     
       10. The assembly of  claim 1 , wherein:
 said retainers comprise shear pins that have the same or different shear ratings for failure. 
 
     
     
       11. The assembly of  claim 1 , wherein:
 said relatively movable component is centralized within said supported component. 
 
     
     
       12. The assembly of  claim 1 , further comprising:
 a locking retainer engaging said components against reversal of said relative movement upon or after engagement of said impact surface on said travel stop. 
 
     
     
       13. The assembly of  claim 1 , further comprising:
 an outer sleeve on said supported component having a backup support shoulder to engage said relatively movable component for retrieval thereof should said travel stop fail to support said relatively movable component by said impact surface. 
 
     
     
       14. The assembly of  claim 1 , wherein:
 said travel stop comprises spaced apart segments on axially extending elongated flexible fingers. 
 
     
     
       15. The assembly of  claim 14 , wherein:
 at least some of said plurality of retainers are supported in said fingers. 
 
     
     
       16. An impact absorbing assembly for a subterranean tool, comprising:
 a supported component comprising at least one travel stop; 
 a relatively moving component having at least one impact surface that selectively engages said at least one travel stop; 
 a plurality of retainers disabled at different times during movement of said relatively moving component before said at least one impact surface lands on said at least one travel stop; 
 said travel stop comprises spaced apart segments on elongated flexible fingers; 
 said flexible fingers are circumferentially spaced to define axial gaps; 
 said at least one impact surface comprises a plurality of impact surfaces; 
 said impact surfaces are insertable into said axial gaps and relatively rotatable into alignment with said travel stops, whereupon insertion of said plurality of retainers retains said components to each other, said components selectively locked to a housing until a mandrel is axially moved in said housing releasing said selective locking. 
 
     
     
       17. An impact absorbing assembly for a subterranean tool, comprising:
 a supported component comprising at least one travel stop; 
 a relatively moving component having at least one impact surface that selectively engages said at least one travel stop; 
 a plurality of retainers disabled at different times during movement of said relatively moving component before said at least one impact surface lands on said at least one travel stop; 
 said travel stop comprises spaced apart segments on elongated flexible fingers; 
 said fingers are placed in tension when said impact surface engages said travel stop causing said fingers to flex radially in opposed radial directions to reduce impact of said impact surface on said travel stop. 
 
     
     
       18. The assembly of  claim 17 , wherein:
 said impact surface comprises circumferentially spaced segments. 
 
     
     
       19. An impact absorbing assembly for a subterranean tool, comprising:
 a supported component comprising a travel stop; 
 a relatively moving component having an impact surface that selectively engages said travel stop; 
 said travel stop comprises spaced apart segments on axially oriented elongated flexible fingers defining axial gaps therebetween. 
 
     
     
       20. The assembly of  claim 19 , wherein:
 said flexible fingers support a plurality of retainers. 
 
     
     
       21. The assembly of  claim 19 , wherein:
 said impact surfaces are insertable into said axial gaps and relatively rotatable into alignment with said travel stops, whereupon insertion of a plurality of retainers retains said components to each other, said components selectively locked to a housing until a mandrel is axially moved in said housing releasing said selective locking. 
 
     
     
       22. An impact absorbing assembly for a subterranean tool, comprising:
 a supported component comprising a travel stop; 
 a relatively moving component having an impact surface that selectively engages said travel stop; 
 said travel stop comprises spaced apart segments on elongated flexible fingers; 
 said fingers are placed in tension when said impact surface engages said travel stop causing said fingers to flex radially in opposed radial directions to reduce impact of said impact surface on said travel stop. 
 
     
     
       23. The assembly of  claim 22 , wherein:
 said impact surface comprises circumferentially spaced segments.